Havaux M, Tardy F
Département d'Ecophysiologie Végétale et de Microbiologie, CEA-Cadarache, Saint-Paul-lez-Durance, France.
J Photochem Photobiol B. 1997 Aug;40(1):68-75. doi: 10.1016/s1011-1344(97)00025-0.
When barley leaves were suddenly exposed to strong white light, the rate of thermal de-excitation of the absorbed light energy, measured with a photoacoustic device, increased by around 12% within a few minutes. This phenomenon was paralleled by a quenching of chlorophyll fluorescence. Simultaneous measurements of the heat emission increase and chlorophyll fluorescence quenching allowed the absolute yield phi F of chlorophyll fluorescence to be determined in vivo; phi F varied from around 2% (at Fo) to around 15% (at Fm) in a variety of plant species. No correlation was found between the time course of heat emission increase and the time course of violaxanthin-to-zeaxanthin conversion in barley leaves exposed to various light and temperature treatments, indicating that the zeaxanthin pool built up in the light was not directly involved in the increased heat emission. However, the operation of the violaxanthin cycle accelerated the photoinduced rise in thermal energy dissipation. Photoacoustic measurements on leaves of a zeaxanthin-accumulating Arabidopsis thaliana mutant lacking the violaxanthin cycle indicated that this acceleration could be ascribed to the disappearance of violaxanthin rather than to the formation of zeaxanthin.
当大麦叶片突然暴露于强光下时，用光声装置测量的吸收光能的热去激发速率在几分钟内增加了约12%。这种现象与叶绿素荧光猝灭同时出现。对热发射增加和叶绿素荧光猝灭的同步测量使得能够在体内测定叶绿素荧光的绝对产率φF；在各种植物物种中，φF在约2%（在Fo时）至约15%（在Fm时）之间变化。在经受各种光照和温度处理的大麦叶片中，未发现热发射增加的时间进程与紫黄质向玉米黄质转化的时间进程之间存在相关性，这表明在光照下积累的玉米黄质库并未直接参与热发射的增加。然而，紫黄质循环的运转加速了光诱导的热能耗散增加。对缺乏紫黄质循环的积累玉米黄质的拟南芥突变体叶片进行的光声测量表明，这种加速可归因于紫黄质的消失而非玉米黄质的形成。
